Petroleum Exploration & Production Research Institute, SINOPEC Coalbed Methane Research Center, China
University of Petroleum (Beiing)

煤层气开发过程中煤岩应力敏感性对渗透率产生影响,而渗透率的变化直接决定着煤层气资源商业开采的成败。试验测定了鄂尔多斯盆地老坑口矿井煤岩在平行面割理、垂直面割理及垂直层理面3个不同方向的渗透率随有效应力变化情况,对比分析了增压过程和降压过程中不同割理方向煤岩应力敏感性差异。结果表明:不同割理方向煤岩应力敏感强烈阶段有所不同,平行面割理方向应力敏感强烈阶段集中在有效应力小于8 MPa,垂直面割理及垂直层理面则分别在6和4 MPa附近;鉴于煤层气井排采中储层应力敏感效应的影响,提出动液面在接近煤层中深200 m后,谨慎降液排采,同时建议实施减小渗透率降低幅度和时间的排采;基于平行面割理方向煤岩渗透率更有优势,因此,井网长轴平行面割理方向是井网部署合理方向。

Coal stress- sensitivity has serious impacts on the value of permeability during coalbed methane development, meanwhile, the permeability change woul d directly determine the success or failure of commercial exploitation of coalbed methane resources. The experimental studies have done for permeability change with d ifferent effective stress in different directions of coal in the Laokengkou mine of southeastern margin of Ordos Basin, such as parallel face cleats, vertical face cleats an d vertical bedding. The comparative analysis of coal permeability loss value accompanying direction changes during the pressurization and step- down process was don e. The results showed that the phases of stress sensitivity were varied in different coal cleat orientation, Where the strong stress sensitivity phase for parallel to the face cleats focuses on the effective stress was less than 8 MPa range, vertical cleats and vertical bedding planes concentrated in less than 6MPa, 4 MPa respectively. Consi dering the impacts of stress sensitivity during drainage for coalbed methane wells in nearly 200 m deep coal seam should carefully extraction, reducing amplitude of per meability reduction and time schedule, were proposed. Based on the permeability advantage of face cleats, the well network layout is the long axis of well network paral leling to the face cleats.

中国石油化工集团科研资助项目(G5800-11-ZS-YTB46)；